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Firefighter SCBA tank for forge

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I know several people that are in the AC business but no one has a freon tank available.   I also know a firefighter.  He has access to expired tanks that are no longer certifiable.  I'm building 2 forges 1 from a 30# propane tank and I want to build a smaller one that will operate on a  single burner.  I'm thinking the SCBA tank might be a great alternative, very long and skinny.  Great for tongs, knives, etc.  Just thought I would pass it along.  I guess used fire extinguishers might work also.

CC

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I was just thinking outside the box.  In my case, a smaller diameter, longer forge might be a better option.  The firefighter has a tank at home available now, the other guys can get me a tank, but it may be a while before they empty one....

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Long and skinny means multiple small burners if you want anything approaching even heat inside the forge chamber.  Depending on the burner size I normally figure about 4 to 6  inches either side of the burner to be the "hot zone."  The temperature seems to me to fall pretty rapidly further than that from the burners I've used.  Of course there are a lot of variables that come into play and your mileage may vary.

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Thanks, I hadn't thought of that aspect of it.  Just thinking of overall volume.  Thanks for keeping me straight, not to say that 2 1/2" burners isn't off the table.  Run 1 for small heated areas, run both for long objects like a knife blade.

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For forging knives you don't need a long forge.  You can only work about 6 inches at a time unless you have a power hammer.  However, when it comes time to heat treat knives a longer forge can make life easier.

Just for reference, my most recent WIP knife has a blade nearly 12 inches long and currently still has about 7 inches of tang (which will be cut down later).  The gas forge I use only has a chamber about 9 inches long (with a pass-through opening), and let's just say that a few more inches of hot steel per heat wouldn't have decreased the time it took to forge.

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Leaving aside forge construction questions, such an item might be good as a quench tank.

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I know Mikey doesn't like it but I still REALLY like stainless steel stove pipe for a cylindrical gas forge. It's available in almost any diameter from 4" to 12 without having to special order or put different diameters together. Snap a 4" and a 5" together for a dia just under 9", etc.

All the standard fittings are off the shelf, wall brackets make perfect legs, caps and bushing reducers make doors and cover Kaowool. For instance, 10" pipe with 2" of blanket refractory. insert an off the shelf, 10" x 6" bushing reducer in one or both ends. A lined 6" plug type cap makes a door. 

The only tools you need are aviation tin snips or a saber saw and hand drill with bits. Hole saws are really handy but not essential. and a pop rivet puller and SS rivets.

Why SS rather than steel stove pipe? SS reflects IR much more effectively than plain steel so the outside of the shell isn't likely to get hot enough to burn anybody or thing and more of that heat you pay for stays IN the forge.

It's more than strong enough by a large factor, think multiples of what's going to crush your ceramic blanket under whatever you use for a floor, strong enough. Heck steel stove pipe is well more than strong enough, you ain't going to heat anything heavier than what, a 5lb. hammer head?

Yeah, SS stove pipe is more expensive, especially if you live somewhere wood heat isn't common. But: off the shelf components, common tools, minimal skills, light weight for stronger than necessary, and more efficient is worth something.

Frosty The Lucky. 

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Another thing I keep forgetting about is cutting a back hole in the smaller tank for longer objects.  That was one reason I went with a 30# instead of 20# propane tank.  Both were easily accessable for me, but I figured I could have the extra length of the 30#, with about the same volume as the 20# tank.  Finished ID should be between 6-7" x 18" long, that's 500-700 cubic inches depending on the ID.  

I just left both HD and Lowes trying to find sonic tube concrete molds, but the smallest they have is 8", way too big for my application.  When I got home I found some old dryer vent, so I'm thinking wrap it with some cardboard until I reach 6.5", and call it good.  It should work well being reinforced with the wire in the dryer vent.  

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Hole saws are great for making pass throughs and you get to keep the hole saw! I like the Bi metal ones, they last a LOT longer under iffy conditions, can't think of the brand though. 

Just find something with an OD you like and wrap it in a couple separate sheets of news paper and one of Saran wrap or the equivalent to hold it in place. When the concrete, refractory, etc. is set you can slip the form out, the news paper layers will yield. Dryer vent is Okay IF you wrap enough news paper around it to cover the texture. Cardboard doesn't work so well, it can get trapped, refractories usually swell or shrink slightly when they set. Multiple layers of news paper won't get trapped as they're unconsolidated (not glued together) like cardboard. The plastic wrap keeps the binder carrying water from the refractory from turning the paper into a low efficiency refractory concrete.

Frosty The Lucky.

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I'm using Mizzou for a refractory.  Will a bi-metal hole saw cut through the Mizzou if cast about 1/2" thick.  I haven't cut through the inswool yet for the burners and would like to cast it without the holes for obvious reasons.  Maybe I should try to carve a 1 1/2" dia piece of styrofoam and go ahead and cut the inswool?  What have others tried for this procedure,  I would rather cast than trowel in 2 or 3 sections due to gravity pulling it off the walls.

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